The Stovebolt Site Forums The Shop Area Driveline Fall Driveline Project

Looks like I have a driveline project for this Fall. I expect that there may be issues getting some parts so I want to order them now so they are on hand. I know that I will find more issues as I go.

Issues:

• Clutch slipping in high gear on moderate slopes. It seems worse after driving for a while.
• Transmission jumps out of second gear into neutral. This happens while going downhill with foot off the gas pedal.
• Shifting from third into second can only be done at very low speed.
• Transmission trying to jump out of fourth gear. The shifter is jerking, but it's not actually jumping out. This only happens with foot off the gas pedal.

The engine is a 1962 235 and the transmission is a 1967 SM420. It has an open 2 piece driveshaft. The truck has not and will not be driven hard; probably biggest load will be acooler and folding lawn chairs.

Parts to be ordered:

• 11" Clutch kit. Kits includes pilot bushing and throwout bearing. Any recommendations on good kits or kits to avoid?
• Flywheel and bolts. A new flywheel seems inexpensive so I expect that nobody resurfaces old ones anymore. Probably wise not to reuse bolts?
• Rear crank seal? I suppose we will see if it's needed when the flywheel is removed.
• Transmission rebuild kit. Syncro "cones" are usually not included in these kits and given the symptoms described above, I think that's what it really needs. I'm still considering simply dropping the transmission off at a shop.

Tools:

• I will have to borrow or rent a transmission jack.
• I don't have a press, but according to some YouTube videos, I believe it's possible to do the job without one.

Any other considerations at this point?

Gord, Harbor Freight has inexpensive transmission jacks and 12 ton presses. I have both and they work well. I see you are north of the border so HF may not be an option.

Martin,
HF is not here, but we have Princess Auto which sells the same sort of stuff. However, I'm getting older and am thinking that in about 20 years I will need to downsize. So when I'm looking at buying new stuff I'm asking myself if I really need it and how much use will it get. Especially thinking about stuff that takes up a lot of room.

Any suggestions on clutch kits?

It's doubtful that just replacing synchro's will help with a tranny that's jumping out of gear. It's more likely caused by worn clutch dogs on the gears (the parts that actually engage), or possibly badly worn bearings. When the gears can move relative to each other, that motion makes the dogs walk out of engagement.

The clutch I bought (although a 9") for my 51 216 was a Luk brand, which should be a good choice.

I thought Canadian Tire was the Harbor Freight equivalent in Canada. I bought a pair of jack stands at Williams Lake on a trip down to the lower 48 when I needed to do some work on my truck in a motel parking lot.

You might consider the following : https://www.ebay.com/itm/304379323271?epid=15011162580&hash=item46de6be387:g:lhgAAOSwSJhiHuuT ( Clutch Gear synchro cone GM 3767292 / 591603
and https://www.ebay.com/itm/142795181464?hash=item213f418d98:g:of8AAOSwL7pa-i5d ( Third Gear GM 591602 / 360894 )
These do pop up occasionally on EBay and yes they are also hard to find.
If you do the rebuild yourself you might consider contacting Novak-adapt.com for one of their rebuild kits.

Well, it's not a good idea to order parts before you actually have them out and on the floor where you can measure them. The only clutch kit that Rock Auto listed for a 1954 truck was a MU5469-1A, so I ordered it. This kit has a 10" clutch disc. Took the clutch out today - it has a 9" clutch disc. The flywheel does not have extra holes for it to accept the kit's larger clutch pressure plate.

Rock Auto shows a 9" clutch for 1953 trucks; MU1042-1.

So, I either find a new flywheel that is designed for an 10" clutch, or get the smaller 1953 clutch kit. A new flywheel is appealing as I would have to get the old one resurfaced anyway. The problem is that Rock Auto does not show a flywheel to match the kit I have.

Gord

You've found hen's teeth with the 9 bolt 10" clutch kit. Others were looking for one.

Maybe your misfortune will help someone else.

Both the old and the new clutch pressure plates are 6 bolts. The kit's pressure plate bolt circle diameter is larger than the one I removed from the truck.